issue_771_add_key_error_if_spaces

[abhishekvickyvyas]

Hello,
Here is my contribution for issue #771 . I raise a key error if prefix have spaces in it. The changes are done is /rdflib/NamespaceManger.bind. Please let me know if error message need to be change or if we need to raise only warning instead of error message.

[coveralls]

Coverage increased (+0.05%) to 75.473% when pulling 4276aa7 on abhishekvickyvyas:master into 7a53c61 on RDFLib:master.

[nicholascar]

Hi @abhishekvickyvyas thanks for addressing this - it's a real error in RDFlib - but your solutions is odd! Perhaps you're using a JavaScript code style in Python??

Rather than:

 if (len(prefix.split(" ")) > 1):
    raise KeyError("\'" + prefix + "\' does not look like a valid prefix as it has spaces, change it into correct format")

How about:

 if " " in prefix:
    raise KeyError("'{}' does not look like a valid prefix as it has spaces".format(prefix))

We do also need a test for any PR (RDFlib policy) so you'll need to write a small test function for this.

If you make this change, and add a test, we'll accept the PR. Thanks (maintainers)